Making photographic silhouette records



NOV 3, 1942 s. DE M. BROWN 2,301,013 MAKING PI'IOTOGRAIHCl SILHOUETVTE RECORDS Filed Jn. 1e, 1940 BLUE T0 YELLOW `S`ENS/7'l/E F/LM; ABSORPT/ON /NCREASING FROM YELLOW TOWARDS COPY/NG W/TH BLUE TO YELLOW LIGHT; NO PRE-EXPOSURE FOR TOE DEVELOP/NG, HARDE/VWG, ErcH/NG, DVE/NG DENS/ 7`Y a 0G EXPOSURE vm f Patented Navas,

y 2,301,013 Msxmdlrno'rocmmc snnoumc i aaconns Stewart De Motte Brown, Iver Heath, England,` assignor to Technicolor Motion Picture Corporation, Los Angeles, Calif., a corporation of Maine v Application January 16,1940, Serial No. 314,059

6 Claims.

Photographic processes may present problem which make it desirable to exaggerate differences in vdensities of photographic records; for example, so-called traveling mattes used for producing certain types of composite motion picture film (as for example described in copending application Serial No. 285,067, filed July 18, 1939, of Leslie W. Oliver) require the differentiation of a record field into a high density and low density area, without detail in these areas. Similar problems may arise invthe production of silhouette effects for pictorial purposes, or of sound tracks tions l and h, respectively. According to well-ii.` known processes, the emulsion portions contain' `ing` exposed silver halide can be hardened, the

unexposed portions etched off, and the remaining relief. colored with dyes. The characteristic curves o f such reliefs, vrelatively to light of the Y range which the dyes therein contained absorb,

of thevarying width type, or, generally speaking,

whenever it is desired to obtain records consisting of areas of maximum density difference on respective sides of a contour.

In the above-mentioned especially important example of traveling mattes, the areas corresponding to original exposure values above a` certain intermediate value should be substanposure values above and below, respectively, an

intermediate value. In another aspect the invention provides a method of making silhouette traveling mattes for purposes of producing special process motion picture film. These and other objects and aspects of the invention will be apparent from the following description of a practical embodiment thereof illustrating the genus of the invention and referring to a drawing in which:

Fig. l is a log exposure-density diagram characterizing one feature of the invention; and

Fig. 2 is the flow diagram of a photographic process incorporating the invention.

With reference to Fig. 1, the characteristics of photographic material used in carrying out this invention will first be described as far as they have a bearing thereon.. As well known,

ordinary silver halide emulsions have a log ex-h posure-density characteristic of the general shape indicated at A of Fig. 1, with a comparatively straight intermediate portion i and much more iiat low density(toe) and high density por' 1 the other.

have for practical purposes no toe and a straight intermediate portion which passes rather abruptly into a constant density portion, as shown at B of Fig. 1. Such reliefs are extensively used as matrices, by dyeing them and transferring their dye to blank films. However, due also to peculiarities of the dye transfer process the` above relief characteristic is rather unsuitable for these purposes, and ways of improving its shape have therefore been proposed.

As disclosed in Patent No. 1,677,665 of July 17, 1928, to Eastman A. Weaver, relief records having a toe can be obtained by pre-exposing or flashing a silver emulsion through its support with light which it absorbs. Patent No. 1,804,727 of May l2, 1931, likewise to Eastman A. Weaver, teaches a method of obtaining gelatine reliefs whose varying thicknesses represent a char' acteristic curvehaving an upwardly concave configuration. This method involves dyeing the film and printing it with two light ranges differently absorbed by the emulsion so that the light of the one range penetrates deeper than An improvement of this method is described in Patent No. 2,044,864, of June 23, 1936, to Leonard T. Troland. By combining the flashing and differential absorption methods Y (using the same absorption property of the emulsion for purposes of pre-exposure flashing as well as differential absorption), a relief having a toe and an upwardly concave intermediate-towardshigh density region, a`s shown at C of Fig. l, can be obtained. Dye transfer (imlcilfition)` prints made with such matrices have a characteristic fairly `similar to that of a silver record according to A of Fig. l. It should be especially noted that the characteristic C corresponds to the varying gelatine thickness of a relief. and the transmission of a dyed relief, or asilver record exposed through such a dyed relief. whereas the actually desired characteristic of the dve transfer record conforms to A of Fig. 1. the differences being due to the above-mentioned peculiarities of the dye transfer process.

VIn accordance with the inventionthe light transmission properties of a film of the above` type which, however, has not been pre-exposed or flashed, at least not to a degree applied for utilized for making silhouette records, as will nowv be described.

In Fig. 2, Fb and Fg are blue and green recording negatives, respectively, of a foreground object with backing, of the nature described in the above copending application, Serial No. 285,067. As explained in that application, it may be desirable to photograph, in natural colors, a given foreground action against a background object field, background and foreground to be taken separately; for example, the foregroundmay be a magic carpet fiying with a person thereon in front of a fanciful background.`

For that purpose, a background object field is illuminated with white light containing the blue, green and red spectral ranges. The foreground, for example a magic carpet set, is likewise illuminated with white light, and has a uniform backing showing as little detail as possible. 'This backing may be painted yellow, with a pigment reflecting substantially only the green and red spectral ranges, and in that case would be illuminated with green and red light.

Both background and foreground with backing are separately photographed with a color separation camera or on integral pack film, according to well-known methods.

There will now exist two sets -of blue, green and red recording negatives, which comprise the above-mentioned blue and green recording foreground with backing negatives Fb and Fg, which alone need be considered for purposes of explaining the present invention. As described in the above-mentioned copending application, the background field may be illuminated as customary for pictures of this type, but the foreground scene with backing, which are recorded on Fb and Fg, should be illuminated in such a manner that the green reflection from the backing (colored and illuminated with minus blue light as mentioned above) is at no point of less intensity and preferably at al1 points of higher intensity than the green refiection from any point of the foreground.

Therefore, the backing area of negative Fb will be essentially clear, since this blue recording film has not received any light from the minus blue backing. On the other hand, the corresponding areas of green recording film Fg will be rather dense, having been exposed to the green and red spectral ranges reected from the backing. The foreground proper will be recorded as usual on color separation negatives of this type but, because of the above-mentioned precaution, the foreground area of negative Fg will nowhere have a density higher than the density f its backing area.

From the blue and green foreground negatives two mattes are now made, for example according to the method indicated in Fig. 2, as follows: A positive Pb is printed from the blue recording foreground negative Fb, and a light sensitive lrn is then consecutively exposed to negative Fg and positive Pb. Since the backing area on bothF-g and Pb is of high density, the latent record o`f this new print BM, herein referred to as background matte, will have low exposure values in the backing area, with little detail. On the other hand, the consecutive printing of a positive and a negative of the foreground scene will furnish a rather highly exposed latent rec- -ord of the foreground area of matte BM.

In the finished matte, the photographic conbe as high as possible, in order to magnify small exposure differences between these areas, s0 that; in the present embodiment, the minus blue backing will be rendered transparent in the matte, and the foreground area uniformly opaque.

According" to the invention, and as indicated at l ofFig. 2, a record of this type is provided by printing negative Fg and positive Pb on a film sensitized to blue, blue-green, green and yellow light with a conventional sensitizing dye as for example erythrosine, and dyed, per 100 g. gelatine, with Tartrazine 10 g.. Rose bengal 0.75 g., and acid magenta 0.125 g. An emulsion of this type is sensitive to a light range from blue to yellow, inclusive, strongly absorbs the blue range, absorbs the green range, and to a slighter degree absorbs the yellow range.- Therefore, its exposure with light including the blue to yellow ranges will have the above-described effect of differential penetration, which is also indicated at 2 of Fig. 2 where lines L, I and H indicate the depth of penetration of the blue, green and yellow light ranges, respectively, the envelope of these lines representing the exposure. It should be noted that the curve is actually even' fiatter in the low density region than possible to show in a schematical straight line diagram and that the subsequent etching step will remove the gela- Vtine in this region if the above-explained ashing technique is omitted.

After the film has been exposed to records Pb and Fg as mentioned above, precautions having been taken that any preexposure or flashing is avoided, it is developed, in a hardening pyro developer, as for example, described in Patent No. 1,535,700, dated April 28, 1925, to Leonard T.

. Troland, and bleached to silver ferro cyanide in f a ferri cyanide bath as described in U. S. Patent No. 1,919,673 of July 25, 1933, to Troland and Eaton. This bleaching reaction produces still further hardening of the developed gelatine portions, corresponding to considerable eilective intensification of the original record. The unhardened gelatine is then removed in a bath of hot water leaving the record in hardened gelatine and silver ferro cyanide. In this manner a gelatine relief is obtained which conforms to cur'. e D of Fig. 1 and is indicated at 3 of Fig. 2.

This relief is then dyed for example with yellow dye as Brilliant Paper Yellow Concentrated (Schultz, 7th ed. #724): If desired, the density of the residual silver ferro cyanide record may be increased by redeveloping it, in well-known manner, to form a silver or silver sulphide record. The resulting record will be essentially y clear or fully transparent for actinic light in trastof background and foreground areas' should 75 the low exposure area, and in the high exposure region substantially opaque for light affecting the usual positive emulsions. Prints made on silver emulsions from such dyed reliefs will therefore likewise have a characteristic curve, as indicated at D of Fig. 1. intensity exposures will up to a certain intermediate value result in a substantially clear record area, Whereaa'beginning with that intermediate exposure value, the corresponding densities will rapidly increase. In other words, for practical purposes, exposure intensities up to a given intermediate value (which ca'n, to a certain degree, be selected at will) are not recorded, Vwhereas substantially allintensities beyond that value will produce 'opaque areas, there being -only a very short half tone region corresponding Due to this shape, low,

sities or practically opaque densities, respectively.

The film MB produced in this manner will therefore constitute a true and effective mask with any detail of the foreground field as well as of the backing being eliminated, the area of the former being for printing purposes opaque gelatine, and that of the latter substantially clear Celluloid from which the gelatine is etched oif,

Matte MB may then be copied on a further film, if desired according tothe above-described procedure; a second or foreground matte with opaque backing and clear foreground areas, respectively, being obtained in this manner.

As described in the above copending application, three matrix films of the type commonly used for that purpose are now exposed to the background negatives, each exposure being limited by means of background matte BM to the background area exclusive of the foreground area represented in the matte by its uniformly opaque silhouette. Therefore, this exposure furnishes latent records of the background combined with an unexposed foreground area., The matrix films are then exposedto the foreground negatives,

including Fb and Fg, through thel foreground matte which screens the previously exposed background area but permits exposure of the foreground area recorded on the foreground negatives. The three matrix films are then developed and converted into gelatine reliefs, from which the final positive is printed according to the well-known imbibition process, this positive constituting a combined lrecord, in natural colors, of separately photographed background and foreground object fields.

It was found that, with the above-described method, from a negative having two areas of densities differing as slightly as about 0.05 silver density, a print can be made in which all gelatine is removed from the area corresponding to the higher negative density, whereas the lower density area of the negative is in the print represented by a dyed gelatine layer having an effective light stopping power equivalent to approximately 1.0 silver density.`

It should be understood that the present disclosure is for the purpose of illustration only and that this invention vincludes all modifications and equivalents which fall lwithinthe scope of the appended claims.V

1. Method of producing photographic silhouette records which comprises taking a record having a density range including high light as well as shade values, copying said record on lan emulsion whose density range includes high light as well as shade values and 'corresponds to an exposure range constituting a comparatively short intermediate section ofthe exposure range of said record, developing said emulsion and ette records which comprises taking a record forming a dye record from the gelatine portions plete density range correspondstoa comparatively short exposure range including said intermediate exposure'value, developing said emulsion, and forming therein a dye record from the gelatine which received an exposure within and above said short exposure range.

' 3. Method of producing photographic silhouette records which comprises taking a record, copying said record on. a substantially unpreexposed emulsion sensitive for two spectral ranges and absorbing less light of one of said ranges than cf the other range, with light containing both ranges, developing and hardening the exposed gelatine portions of said emulsion, removing the non-exposed gelatine portions thereof thereby providing a relief record, coloring said relief reccrd with strongly light absorbing dye, and copying said relief record with light absorbed by said dye. i

4. Method of producing photographic silhouette records which comprises taking a record, copying said record on a substantially unpreexposed emulsicn sensitive for two spectral ranges and absorbing less light of one of said ranges than of the other range, with light containing vboth ranges, developing and hardening the exhouette which comprises sensitizing` a photo-1` graphic` film for two spectral rangesfdyeing it to absorb one of said ranges stronger than the other, copying on said film a record having high density areas and low density areas with light of saidtwo ranges of such intensity that the high density areas of said record are only slightly reproduced on said film due to high absorption in the filml of one of said ranges and the low density areas of said record are strongly reproduced due to high transmission in the film of the other range, developing said film, substantially removing from the film the gelatine over the areas corresponding to said high densities, and rendering the remaining gelatine substantially, opaque.

6. Method of producing a photographic silhouette which .comprises sensitizing a photographic film 4for two spectral ranges, dyeing it to absorbone of said ranges stronger than the 4 f sity areas of said record are strongly reproduced having a density range substantially divided into v two record area groups whose densities are on Y either side respectively of a density value corresponding to an intermediate exposureV value, i

copying said record on Van emulsion whose comdue to high transmission in the film o! the other range, developing said film; substantially removing from the film the gelatine over the areas corresponding to said high densities, and rendering the remaining gelatine substantially opaque. A

STEWART DE MO'I'IE BROWN. 

